scholarly journals High water level observations along the upper course of the Olt River (Romania) from a hydrological modelling aspect

2017 ◽  
Vol 11 (2) ◽  
pp. 10-19
Author(s):  
Noémi Mária Szopos ◽  
Boglárka Czellecz
Keyword(s):  
Hydrological Modeling ◽  
River Flow ◽  
High Water ◽  
Main Channel ◽  
Flood Events ◽  
River Section ◽  
Modeling Software ◽  
Section Model ◽  
Hydrometric Station ◽  
River Cross Section

Along its upper course, the Olt River (Romania) flows through several settlements, which are endangered by flooding. The multiannual water flow at Tomești station, the first hydrometric station along the Olt River, is 1.51 m3 /s, but in case of extreme events the river flow reached even 41.8 m3 /s. The aim of this study is to analyze the flood events along the upper course of the Olt River (section between Tomești and Cârța settlements) by using the HEC-RAS and the HEC-GeoRAS hydrological modeling software programs. The river cross section model showed how the main channel narrowed (characteristic to some locations) which can be considered as one of the causes of a possible overflow.

scholarly journals Hydraulic Evaluation of the Levee System Evolution on the Kurobe Alluvial Fan in the 18th and 19th Centuries

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4406
Author(s):  
Tadaharu Ishikawa ◽  
Hiroshi Senoo
Keyword(s):  
Channel Capacity ◽  
Flood Control ◽  
River Flow ◽  
Global Climate ◽  
Flow Simulation ◽  
Japan Sea ◽  
Main Channel ◽  
Alluvial Fan ◽  
Flood Peak ◽  
Levee System

The development process and flood control effects of the open-levee system, which was constructed from the mid-18th to the mid-19th centuries, on the Kurobe Alluvial Fan—a large alluvial fan located on the Japan Sea Coast of Japan’s main island—was evaluated using numerical flow simulation. The topography for the numerical simulation was determined from an old pictorial map in the 18th century and various maps after the 19th century, and the return period of the flood hydrograph was determined to be 10 years judging from the level of civil engineering of those days. The numerical results suggested the followings: The levees at the first stage were made to block the dominant divergent streams to gather the river flows together efficiently; by the completed open-levee system, excess river flow over the main channel capacity was discharged through upstream levee openings to old stream courses which were used as temporary floodways, and after the flood peak, a part of the flooded water returned to the main channel through the downstream levee openings. It is considered that the ideas of civil engineers of those days to control the floods exceeding river channel capacity, embodied in their levee arrangement, will give us hints on how to control the extraordinary floods that we should face in the near future when the scale of storms will increase due to the global climate change.

Study on 3D Fine Structural Modeling of Typical Block in Sanan Oilfield, Daqing

2014 ◽  
Vol 628 ◽  
pp. 348-353
Author(s):  
Tao Li ◽  
Zian Li ◽  
Jiang Wang
Keyword(s):  
Structural Model ◽  
3D Structure ◽  
High Water ◽  
Oil Distribution ◽  
Remaining Oil ◽  
Modeling Software ◽  
Remaining Oil Distribution ◽  
High Water Cut ◽  
Reservoir Description ◽  
Water Cut

Sanan oilfield has entered late stage of high water cut development. It urgently needs accurate prediction of remaining oil distribution. But previous studies on 3D structure were far could not meet the requirements of fine reservoir description. This paper applied RMS, a piece of excellent geological modeling software establishing the 3D fine structural model of typical block in Sanan oilfield on the bases of 3D fine seismic structural interpretation data. It included the 28 faults’ model, 11 horizons’ model and the structural model. And then measured and analyzed the faults elements data. Based on abundant geologic data, well data and seismic data of the block, this structural model reproduced the fine seismic interpretation results accurately. It was really fine enough to meet the requirements of the fine reservoir description. This research solved the problem that traditional modeling techniques could not handle complex cutting relationship of faults’ model. It laid a solid foundation for reservoir numerical simulation and remaining oil distribution prediction.

scholarly journals Experimental Study of Submerged Vanes in Intakes under Sediment Feeding Conditions

2018 ◽  
Vol 40 ◽  
pp. 03016
Author(s):  
Aslı Bor Türkben
Keyword(s):  
Water Intake ◽  
River Flow ◽  
Flow Direction ◽  
Main Channel ◽  
Bed Topography ◽  
Before And After ◽  
Submerged Vane ◽  
Solid Discharge ◽  
Submerged Vanes ◽  
Intake Structure

Sediment is transported along the river flow and deposited in the mouth of the intake structure over time and reducing the water intake capacity. Nowadays, many water intake structures lose their function and are closed to operation. To deal with this problem, recently, submerged vane application has offered a practical and economical solution. The aim of this study was to evaluate the efficiency of three vane installations under sediment feeding conditions by comparing the bed topography before and after vanes were installed. For that purpose, experiments were carried out in a laboratory channel running for 90-degree intake angle. Three vanes were installed in one column at near the intake entrance. The vanes dimensions were equal to; 3cm height, 12cm long, 10 mm thick, and aligned with α = 20° angle to flow direction. The tests were run until equilibrium was reached, i.e. when the outgoing solid discharge was equal or larger than 90% of the incoming. Once the bed topography remained stable, bed and water level surfaces were measured. tests were carried out by feeding sediment from upstream of the main channel.

Sediments of the Tay Estuary. II. Formation of Ephemeral Zones of High Suspended Sediment Concentrations.

1975 ◽  
Vol 75 (1-2) ◽  
pp. 65-89 ◽  
Author(s):  
A. T. Buller
Keyword(s):  
Suspended Sediment ◽  
River Discharge ◽  
High Tide ◽  
High Water ◽  
Main Channel ◽  
Tidal State ◽  
Suspended Sediment Concentrations ◽  
High Concentrations ◽  
Calm Weather ◽  
Dry Out

SynopsisDuring periods of sustained moderate river discharge and quiescent marine conditions little external suspended sediment enters the estuarine circulation of the Tay. That material which is in suspension is largely derived from the estuary margins where tidal currents superimposed by wind-induced waves are competent to resuspend fine material from the surface of the ‘mud’ flats and erode bedded silts from the incised banks of minor channels and runnels draining them. The quantities of this sediment entering the system are largely determined by tidal state and amplitude, as well as wind velocity.On spring tides the flats are entirely covered at high water, and dry out completely at low water. The volume of water and its areal coverage at high tide ensures that, during the ebb, water charged with high concentrations of suspended sediment is directed from the fiats into the surface and middepth waters of the main channel. This process acting along the 20 km length of the channel flanking the ‘mud’ flats, combined with the low tide ‘ponding effect’ caused by the tide flooding from the sea while the upper estuarine water is still ebbing, results in the cumulative formation of a zone of high suspended sediment concentrations (turbidity maximum). As the flood tide becomes fully established the zone is diluted and dispersed. During neap tides the same processes operate, but because a smaller area of the flats is covered at high water and uncovered at low water, and because neap tidal current speeds are lower than those for spring tides, two proportionally weaker zones are recognised.Following periods of sustained moderate river discharge, quiet sea conditions and calm weather, suspended sediment concentrations in the Tay are negligible irrespective of tidal state or amplitude.

scholarly journals Toward the understanding of saline water intrusion and nutrient flushing in Lake Nokoué

2021 ◽  
Author(s):  
Metogbe Djihouessi ◽  
Rita Houngue ◽  
Firmin Adandedji ◽  
Luc Sintondji
Keyword(s):  
Water Quality ◽  
Atlantic Ocean ◽  
Water Level ◽  
Water Flow ◽  
River Flow ◽  
Saline Water ◽  
High Water ◽  
The North ◽  
High Water Period ◽  
Mike 21

To understand the salinity dynamic at the outlet of Lake Nokoué and to simulate the nutrient flushing from this lake into the Atlantic Ocean, a 2D hydrodynamic model was designed with Mike 21. The choice of the Mike 21 was motivated by the long practice that decision-makers in Benin have with this software. The Hydrodynamics (HD) module simulated water level variations and flows in response, while the ECO-Lab module has been used for water quality modelling. The data used covered the hydrological period of 2013. The results from the HD simulation indicated that for a flow of 725 m3/s at Bonou on the Ouémé River, a tributary of Lake Nokoué. 70% of the land in the delta of Ouémé, between the Ouémé River and the So River (also a tributary of Lake Nokoué), are flooded against 90% for a river flow of 1100 m3/s. The water level in the delta showed a water increase of 0.6 m, in seven days, for a water flow of 725 m3/s at Bonou and a water increase of 1.3 m, in seven days, for a water flow of 1100 m3/s at Bonou. Water quality simulations indicated that the seawater intrusion from the Atlantic Ocean into Lake Nokoué occurred from the bottom to the surface towards the surface of the lake. During flooding, despite the large inflow of fresh water, more than 60% of the water at the bottom of the lake had concentrations greater than 8. Simulation of the dispersion of nutrient point source pollution indicated that there was an accumulation of pollution at the bottom of the lake during low water periods. This accumulation increases in amplitude as one moves away from the Atlantic Ocean towards the north of the lake. In this period tidal flushing evacuated about 20% of the pollution ejected. In the high water period, about 70% of the pollution ejected in the lake was automatically flushed out in the lake the Atlantic Ocean.

scholarly journals A New Method for Extracting Elevation Information of River System from Contours

2019 ◽  
Vol 2 ◽  
pp. 1-7
Author(s):  
Guifang He ◽  
Minshi Liu
Keyword(s):  
River Flow ◽  
Spatial Relationship ◽  
River System ◽  
New Method ◽  
River Section ◽  
Trend Surface ◽  
Existing Problems ◽  
Logical Error ◽  
Conventional Methods ◽  
Low Efficiency

<p><strong>Abstract.</strong> Considering the existing problems in methods of extracting elevation in river system, such as low efficiency, low accuracy, elevation logic errors and other issues, this paper proposes a new method of elevation extraction based on contours. Firstly, the spatial relationship between river system and contours is constructed to improve the intersection efficiency. Secondly, the accuracy of river system elevation can be improved and river flow logical error can be avoided by using the method of interpolation of trend surface of the river section. And then, the river tree is established to avoid the logical error of river system. Many comparison experiments about efficiency, elevation accuracy and elevation logical error between this method and other two conventional methods have been carried out, and the results show that both accuracy and efficiency can be improved and there is no logical error of elevation by this method.</p>

scholarly journals Probabilistic Assessment of Monthly River Flow Discharge Using Copula And OSVR Approaches

2021 ◽  
Author(s):  
Mohammad Nazeri Tahroudi ◽  
Rasoul Mirabbasi ◽  
Yousef Ramezani ◽  
Farshad Ahmadi
Keyword(s):  
River Flow ◽  
Garch Model ◽  
Support Vector ◽  
Monthly Precipitation ◽  
Arch Models ◽  
Vector Autoregressive ◽  
Flow Discharge ◽  
Simulation Results ◽  
Hydrometric Station ◽  
Hydrology And Water Resources

Abstract Simulation of flow discharge based on monthly precipitation values as inputs is one of the important issues in hydrology and water resources studies, especially in areas where data with the shorter time scales are not available. In this study, the applicability of support vector regression (SVR) model optimized by Ant colony and Copula-GARCH algorithms was investigated and compared to simulate the flow discharge based on total monthly rainfall in Talezang Basin, Iran. Entropy theory was used to select a suitable meteorological station corresponding to a hydrometric station. The vector autoregressive model was also used as the base model in Copula-GARCH simulations. The correlation results of the studied paired variable confirmed the possibility of using copula-based models. The simulation results were evaluated using R2, Nash-Sutcliffe Efficiency (NSE) and root mean square error (RMSE) statistics. According to the 99% confidence intervals of the simulations, the accuracy of both models was confirmed. The simulation results showed that the Copula-GARCH model was more accurate than the optimized SVR (OSVR) model. Considering the 90% efficiency (NSE = 0.90) of Copula-GARCH approach, the results show a 36% improvement of RMSE statistics by Copula-GARCH model compared to OSVR model in simulating the flow discharge on a monthly scale. The results also showed that by combining nonlinear ARCH models with the copula-based simulations, the reliability of the simulation results increases, which was also confirmed using the violin plot. The results also showed an increase in the accuracy of the Copula-GARCH model at the minimum and maximum values of the data.

scholarly journals A Comparative Analysis of Exceptional Flood Events in the Context of Heavy Rains in the Summer of 2010: Siret Basin (NE Romania) Case Study

2018 ◽  
Author(s):  
Gheorghe Romanescu ◽  
Alin Mihu-Pintilie ◽  
Cristian Constantin Stoleriu ◽  
Donatella Carboni ◽  
Larisa Elena Paveluc ◽  
...  
Keyword(s):  
Comparative Analysis ◽  
Flood Events ◽  
Flood Wave ◽  
The North ◽  
Maximum Discharge ◽  
Hydrometric Station ◽  
Mountainous Basin ◽  
The City ◽  
Heavy Rains

The Siret River crosses NE Romania from the north to the south and it discharges into the Danube, near the city of Galati. During the period, 17th June - 10th July 2010, significant amounts of precipitations in the mountainous basin of Siret were recorded. The floods comprised two periods with four bimodal cycles and they were counted among the strongest on the Romanian territory. The exceptional floods occurred in the rivers of Siret, Suceava, Moldova, Bistrita, Trotus and so on. The most important compound flood wave was determined by the precipitations which fell within the period, 29th June to 1st July 2010, when significant amounts of rain were recorded, sometimes, exceeding 80 mm. The high discharges on the Bistrita River &ndash; downstream from the Bicaz Reservoir &ndash; were controlled by complex hydro technical works. The maximum discharge for the year 2010 summer floods was recorded at Dragesti hydrometric station: 2,884 m3/s (historic discharge) compared to the preceding historic discharge of the year 2008 (2,850 m3/s). The effects of floods were strongest in the counties of Suceava, Neamt, and Bacau. The floods on the main course of the Siret River were analyzed in correlation with the tributaries within the mountainous sector.

scholarly journals Estimation of Initial Abstraction for Hydrological Modeling Based on Global Land Data Assimilation System–Simulated Datasets

2020 ◽  
Vol 21 (5) ◽  
pp. 1051-1072
Author(s):  
Yanchen Zheng ◽  
Jianzhu Li ◽  
Lixin Dong ◽  
Youtong Rong ◽  
Aiqing Kang ◽  
...  
Keyword(s):  
Hydrological Modeling ◽  
Pearson Correlation ◽  
Driving Factors ◽  
Influential Factor ◽  
Efficiency Coefficient ◽  
Hydrological Models ◽  
Flood Events ◽  
Flood Peak ◽  
Initial Abstraction ◽  
Maximal Information Coefficient

AbstractInitial abstraction (Ia) is a sensitive parameter in hydrological models, and its value directly determines the amount of runoff. Ia, which is influenced by many factors related to antecedent watershed condition (AWC), is difficult to estimate due to lack of observed data. In the Soil Conservation Service curve number (SCS-CN) method, it is often assumed that Ia is 0.2 times the potential maximum retention S. Yet this assumption has frequently been questioned. In this paper, Ia/S and factors potentially influencing Ia were collected from rainfall–runoff events. Soil moisture and evaporation data were extracted from GLDAS-Noah datasets to represent AWC. Based on the driving factors of Ia, identified using the Pearson correlation coefficient and maximal information coefficient, artificial neural network (ANN)-estimated Ia was applied to simulate the selected flood events in the Hydrologic Engineering Center Hydrologic Modeling System (HEC-HMS) model. The results indicated that Ia/S varies over different events and different watersheds. Over 75% of the Ia/S values are less than 0.2 in the two study areas. The driving factors affecting Ia vary over different watersheds, and the antecedent precipitation index appears to be the most influential factor. Flood simulation by the HEC-HMS model using statistical Ia gives the best fitness, whereas applying ANN-estimated Ia outperforms the simulation with median Ia/S. For over 60% of the flood events, ANN-estimated Ia provided better fitness in flood peak and depth, with an average Nash–Sutcliffe efficiency coefficient of 0.76 compared to 0.71 for median Ia/S. The proposed ANN-estimated Ia is physically based and can be applied without calibration, saving time in constructing hydrological models.

scholarly journals Simulating stream flow over data sparse areas – an application of internet based data

2011 ◽  
Vol 8 (6) ◽  
pp. 11015-11037
Author(s):  
M. T. Vu ◽  
S. V. Raghavan ◽  
S. Y. Liong
Keyword(s):  
Hydrological Modeling ◽  
River Flow ◽  
Shuttle Radar Topography Mission ◽  
Observation Data ◽  
Food And Agriculture ◽  
Internet Resources ◽  
Modeling Studies ◽  
Food And Agriculture Organization ◽  
Main River ◽  
Main River Channel

Abstract. Many hydrological modeling studies suffer from lack of robust station observed data, mainly rainfall and discharge. Where such a dearth of data exists, detailed modeling studies in estimating and assessing change in water resources become difficult when models cannot be compared against recorded observations. In addition, some river basins exist along trans-boundaries of two or more countries that problems in data sharing among them add to the difficulties in such modeling studies. Nevertheless, with the advancement in the global internet resources, access to such data has become easy. Whether such internet based data are good substitutes for station data can be ascertained only after performing some modeling research. To this end, this paper describes a hydrological modeling study that simulates the river flow of the Da River across the trans-boundary regions of China and Vietnam over a 11 yr period from 1971 to 1982. Globally available observation data used in this study include topography (from SRTM – Shuttle Radar Topography Mission), land use (from GLCC – Global Land Cover Characterization), soil (from FAO – Food and Agriculture Organization), precipitation (from APHRODITE – Asian Precipitation Highly Resolved Observational Data Integration Towards the Evaluation) and temperature (from GHCN2 – modified of Global Historical Climatology Network version 2). The study employs a hydrological model to recreate the natural flow without dam(s) built across the main river channel. The results of the study are promising and provide a wide scope to utilize internet based data for further research. This also has implications in the context of climate change applications.

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